This application describes a collaborative project between the laboratories of Linda Gooding and William Wold on the relationship between tumor necrosis factor (TNF) and the E3 transcription unit of adenovirus. TNF is secreted by macrophages in response to inflammatory stimuli. It has diverse biological functions which include regulation of cells involved in immunity and inflammation, cytolysis of certain tumor cells, and inhibition of viral replication. We have found that TNF lyses cells infected by human group C adenoviruses with deletions in early region E3. Uninfected cells and cells infected by wild type adenovirus are not lysed. These results indicate that adenovirus renders cells susceptible to TNF, and that a product of region E3 protects against lysis. We have mapped TNF resistance to a gene encoding a 14.7K protein in region E3 and have definitively identified this protein species. Significantly, 14.7K shares sequence homology with interferon B2 (IFN B2). IFN B2 is induced in cells treated with TNF and its presence correlates with cellular resistance to lysis by TNF. We postulate that the 14.7K protein evolved to protect virus infected cells from TNF by mimicking IFN B2. Our major goals are to understand in molecular terms how the 14.7K protein protects against TNF, and how adenovirus induces susceptibility to lysis by TNF. This basic understanding eventually should help us to develop strategies for employing TNF as an anti-viral and an anti-cancer agent. Our specific aims are to purify and characterize 14.7K; to map functional domains within the protein, to study the mechanism of 14.7K function, to determine the relevance of 14.7K expression to pathogenesis among adenovirus serotypes; and to map the adenovirus gene that induces cellular susceptibility to TNF. These specific aims represent, in our view, an ideal merging of the expertise of two laboratories: that of L. Gooding in TNF and other areas of molecular and cellular immunology, and that of W. Wold in the molecular biology of adenovirus region E3.